New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/coding/coding_tests/hex_test.cpp

@@ -0,0 +1,52 @@
+#include "testing/testing.hpp"
+
+#include "coding/hex.hpp"
+
+#include <cstddef>
+#include <cstdint>
+#include <random>
+#include <string>
+
+using namespace std;
+
+UNIT_TEST(GoldenRecode)
+{
+  string data("\x01\x23\x45\x67\x89\xAB\xCD\xEF");
+  string hexData("0123456789ABCDEF");
+
+  TEST_EQUAL(ToHex(data), hexData, ());
+  TEST_EQUAL(data, FromHex(hexData), ());
+}
+
+UNIT_TEST(RandomRecode)
+{
+  mt19937 rng(0);
+  for (size_t i = 0; i < 256; ++i)
+  {
+    string data(1 + (rng() % 20), 0);
+    for (size_t j = 0; j < data.size(); ++j)
+      data[j] = static_cast<char>(rng() % 26) + 'A';
+    TEST_EQUAL(data, FromHex(ToHex(data)), ());
+  }
+}
+
+UNIT_TEST(EncodeNumber)
+{
+  TEST_EQUAL(NumToHex(uint64_t(0x0123456789ABCDEFULL)),
+                                "0123456789ABCDEF", ());
+}
+
+UNIT_TEST(DecodeLowerCaseHex)
+{
+  TEST_EQUAL(FromHex("fe"), "\xfe", ());
+}
+
+UNIT_TEST(EncodeEmptyString)
+{
+  TEST_EQUAL(ToHex(string()), "", ());
+}
+
+UNIT_TEST(DecodeEmptyString)
+{
+  TEST_EQUAL(FromHex(""), "", ());
+}